Motor control.



PATENTED MAY 28, 1907.

Wu B'AY.

ENTER L NTRGL,

APPLZIUATION FILED 001315, 1906.

M75 nesses UNrrnn sra'rss PATENT MAXWELL w. DAY, OF SCHENECTADY, NEW YosnAssIe oR 'ro GENERAL ELECTRIC COMPANY, A CORPORATION or mrwross MOTQR CONTRQL,

To all whom it may concern:

Be it known that I, MAXWELL W. DAY, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Motor Control, of which the following is a" specification.

My invention relates to the control of electric motors for driving loads over wide ranges of speed.

For certain kinds of motor drivers, in which wide ranges of speed are required, such as in the operation of gun turrets and printing presses, it has been proposed heretofore to employ two motors, the smaller of which is geared to the load through -speed-reducing gearing so as to start and drive it at low speed, while the larger motor is geared so as to drive the load'at high s eed. The smaller motor is ordinarily provic ed with a clutch so that it can be dlsconnected from the load when the larger motor is operating. The method of speed control that has usually been employed heretofore for such a combination, is the resistance method but in cases where a constant speed is desired for an, given position of the controlling'switch with varying load, resistance control is not suitable, since the voltage drop in the resistance varieswith varying load on the motor. In such cases a voltage control 'is preferable,

. but since the smaller motor must be out out at its highest speed, and the larger motor simultaneously out in at its lowest speed, the usual methods of voltage control make a quick and smooth transition from one motor to the other difficult to obtain.

My invention consists in deriving from a constant potential source two interdependent voltages respectively, and providing means for varying the two voltages simultaneously but oppositely. Thus, when the voltage for the smaller motor is at its maximum value,

- the voltagefor the larger motor is at its mini- 45 mum value, so that a smooth transition may be made from one to theother. v

More specifically stated,"my invention consists in employing a pair of mechanically con nected shunt wound regulating machines connected in series acrossthe supply-circuit and connecting the two driving motors in parallel with the two regulating machines,

respectively. By varying the relative field strengths of the two machines, the voltage of Specification of Letters Patent.

Application filed October 15, 1906. Serial No. 388,891.

the speed and voltage of the high-speed H10?" tures, and B B the fields of the two regulat- ?atented May as, leer.

' I the point of connection between the two machines may be variedwith respect to either. of the supply oonductors'sj. With this arrangement by opening thecircuit oi the high-speed motor, the low-speed motor may be started. with a low voltage across its' terminals.

Then by adually increasing the fieldstrength o1 the re ulating machine with Y which it is connectein parallel, the voltage supplied to the low-speed motor .1119. he

gradually raised to its maximum. on

this point is reached, the voltage across the other regulating machine will be at its minimum, so that by closing the circuit of the high-speed motor in parallel with the second regulating machine, the'highspeed motor is operated at low s eed. The low speedjno tor may be then isconnected from the 'load' and by gradually increasing the relative field;- strength of the second regulating machine,

tor may be gradually raised to its maximum; In this manner a smooth transition is ob .tainedfrom one motor to the other. My invention further consists in compounding the regulatingmachines by providin each of these with field winding inserted. in, series with the motor whith is in parallel with that machine. By means of this arrangement, the volta e supplied to each motor in any position o the controller is maintained practically constant, especially pt 15W voltage regardless of variations in the My invention will best.beun'derstood with. reference to the accompanying drawing,

- which shows diagrammatically a motor control system arranged in accordance with my invention.

In the drawm A A represent the arms.

ing machines, which are connected in scries 1 between the conductors a, a, which are con-- nected to the supply means 0, Yb. 1 The point of connection between the annatures A and 100 A is'connected through the series field wired ing D and reversing switch Eto one terminal. of the motor armature F, and is also cone-1,.- nected throu h the field winding D, and re versing switc E to one terminal of the m'o-"t tor armature G, The shunt fields F and Gilli-eg of these motors are connected across the con ductors a, a. in series or paralleh H represents a driven member which is trolled.

sequently starts with low follows: With rover-sin two or the other, eccer .poiiit near the lower end 0 this armature runs idly? by tbctixvee, the gear I end liepreseiits e iegule means'oi which the rel of the ve regulating The operation of the s switch C in its "first operative oo matures snd'tlie fields of tw i. chines are connected in sories ZULOSS tlie gley conductors, endthe point of conesi.

tween the fields B and i3- ccmiected to g the Neerly all the resistence K is in the shunt to the field B, While is practically short-circuitod. eoross the terminals of mmsti quently nearly equal to the hile the voltage the low. The motor armature G',"Nlll0 l1 coi1- nected parallel with the ermeture A, 0031" voltage. Sine circuit of clutch is closed. by "i switch G, the driven member E is ii'iflvl 2 low speed. The circuit of the open" at the controlling switch t er As tl e co switch is moved into its second. positior circuit connections remain miclisnged thet the point of connection B and B is shifted to e second poi I resistance K, so as to include more resistczice the entire voltage of the supply circuit.

in shunt to field B. voltage across ermature A is there.) reised Wliile vol" '0 across the armature 1%; is lowered, and the motor G speeds up, increasing the speed st the driven member; In its third, fourth, filth and sixth positions, the controlling switch sti l further increases the voltage across the err; eture A and consequently the speed of semeture G. In the sixth position of the con troller, the armature G is receiving neei ly passing from the sixth to seventh position of the controller C, .the circuit of clu ch (l is opened, and the circuit the mo time F is closed. The motor armature Q: is thus disconnected from the load, while the motor F drives the load st its low By properly proportionin the amount of re sistence K in shunt to toe field of the two regulating mechi ics, this trensition from motor G to motor F may be made very smoothly. As the controller C is moved through its remaining positions, the resistonce is gradually cut into the shunt circuit of field B, and out of the shunt circuit of iield B, so as to greduclly raise the voltage supplied. to imotor armature l end consomotor G, which ties of the controller.

l) serves to maini ermetui'e for any *oller vlziie the motor sop ended to driven, cs ecities,

7 may be driven secede, com '11s for de ve iriotozs,

' simultaneously but JO be driven,

the lo ed and may be driven llereot speeds, at circuit, means ior s 01 tee respective motors, means mg said voltages simultaneously but ,1 positely, and for alternately breaking the circuit of the larger motor and dis connecting; the smaller motor from the load.

3. In combiiietion with load to be driven, two electric motors of ditlereiit capacities, nhenicel conn Between the load and day be driven 'i-s'ent speeds, e A J circuit, means for circuit two interdependvol gee i'or me respective motors, means for varying; voltc es simultaneously but oppositely, em egnetic clutch between the smaller motor and the iced, and means for alternately ores-king the circuit of the larger motor end of the clutch.

{1. In combination with load to be driven, two electric motors of diiicrerit capacities, loW-sr-eed gee-ring between the smaller motor and. toe iced, lii liepeed. eering between the larger motor one the leery-e constei'it potenr sp ed ofthe driven.

capacities thy decreased.

approximately conv it two interdepend- 5. In combination with a load to be driven,

two electric motors of different capacities,

low-speed gearing between the smaller inc-- tooand the load, high-speed gearing between the larger motor and the load, a constant po tential supply circuit, means for deriving from said circuit two interdependent voltages for the respective motors, means for varying the said oltages simultaneously but oppositely, said gearing being arranged to give the same load-speed with the smaller motor opcrating at maximum voltage and with the larger motor operating at minimum voltage, and means for mechanically disconiecting the smaller motor from the load when the larger motor is driving the load.

6. In combination. ith a load to be driven, two electric meters 01 di'll'erent capacities, low-specd gearing between the smaller motor and the load, high-speed gearing between the larger motor and the load, constant potenvtial supply circuit, means for deriving from said circuit two interdependent voltages for the res pectiv motors,,mean s for varying the said voltage si'inultaneously but oppositely,

saidv gearing being arranged to give the same load-speed with the smaller motor operating at maximum voltage and with the larger motor operating at minimum. voltage, and 1 ans l'or alternately breaking the circuit of ti e larger motor and mechanically disconnecting the smaller motor .l'rom the load.

7. In'combination with a load to be driven, two electric motors of dill'erent capacities, mechanical connections between the load and both motors, whereby the load may be driven by either motor but at different speeds, a constant potential supply circuit, means for deriving from said circuit two independentvoltages for the respective motors, means for varying said voltages simultaneously but oppositely, and controlling means for both motors arranged to operate said motors alternately to drive the load.

8. In combination with a load to be driven,

two electric motors of different capacities,

low-speed gearing between the smaller motor and the load, high-speed gearing between the larger motor and the load, a constant potential supply circuit, means for deriving from said circuit two interdependent vol tages for the respective motors, means for varying the said voltages simultaneously but oppositely, said gearing being arranged to give the same load-speed with the smaller motor operating at maximum voltage and with the larger motor operating at nnnimum volthe circuit of said clutch and tage, and controlling means for both motors arranged to operate said motors alternately to drive the load. g

9. In combination, an electric circuit, a I pair of mechanically-connected regulating 7o machines connected in series across said circuit, means for varying the relative field strengths of said machines, two motors connected in parallel with said regnlatingmachines respectively, a load mechanically con- 7 5 nected to both motors, and means for controlling'the operation of both motors for driving the load.

', 1.0. In combination, an electric circuit, a.

pair of mechanically-connected regulating 8( machines connected in series across said circuit, means for varying the relative field strengths of said machines, two motors connected in parallel with said regulating machines respectively, a load mechanically con- 5 nected to both motors, and controlling means for both motors arranged to operate said motors alternately to drive the load.

11. In combination, an electric circuit, a pair of mechanically-connected regulatingii o machines connected in series across said circuit, means for varying the relative field strengths of said machines, two motors connccteo' in parallel with said regulating machines respectively, a load to be driven, me- 5 chanical connections from said load to said motors whereby said lead may be driven by either motor but at difterent speeds, and controlling means for both motors arranged to operate said motors alternately to drive the load.

12. In combination, an electric circuit, a pair of mechanically-connected regulating machines connected in series across said circuit, means for varying he relative field; strengths of said machines, two motors connected in parallel with said regulating anachines respectively, a load mechanical? don; nected to both motors, a magnetic clu ch be?? tween the load anldone motor, andla con- 11o trolling switch arranged to close alternately the circuit of the other motor.

13. In combination, an electric circuit, a pair of mechanically connected regulating machines connected in series acrosss aid circuit, means for varying the relative field strengths of said machines, two motors connected in parallel with said machines respec tively, a load to be driven, mechanical connections from the load to said motors whereby said load may be driven by either motor but at different speeds, a magnetic clutch between the load and .the low-speed motor, and a switch arranged to close alternately the cir- 7 cult of said clutch and the circuit of the highspeed motor.

14. In combination, an electric circuit, a pair of mechanically-connected regulating.

machines connected in series across said cir 1 o cult, two motors connected in parallel with said machines, respectively, a load to be driven, mechani cal connections from the load to said motors whereby said loml may be driven by either motor but st different speeds, a magnetic clutch between the loadand the low-speed motor, and a controlling switch having its contacts arranged,"first; to close the circuit of said clutch and gmdii'ztlly to increase the field strength ofithe sew flitting, machine kg' parallel with the low-speed motor relative to the other regulating machine, eriri" then to open the clutch circuit, close the circuit of thehigh speed motor, and gradually increase therelstive field strength of the reg ulating machine in parallel with thek'highspeed'motor.

15. In combination, an electric circuit, a pair of mechenicelly-connected shunt-wonnd regulstin machines having their srlneti ires connecte in series across said circuit, moses. for varying the relative strengths of the 'connectee in -Shunt iielzls connected in spectively, s loed arranged to be driven by shunt fields at the inechines, a motor con- .nected jn perellel with one of Silld machine s,

end a field winding for said machine con- 15 elected in series with sand motor.

\ 16. in combmetion, an electric circuit, it

Their of mechanically connected shunt-Wound reguletin machines having their 'armetures series ecross'seid circuit, means 30 the relative strengths. of the of said machines, two motors parallel with said machines refor varying eitli ater, and field windings for said reg'u- 5 lilting machines in series with the two motors respectively;

v in Witness whereof", I have hereunto set my hand this 13th day of @ctooer, 1906.

MAJJU/VELL W. DAY. 

